Use gpu::Mailbox in IPCs instead of std::string

content/renderer/browser_plugin/browser_plugin_manager_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/browser_plugin/browser_plugin_manager_impl.h"
 
 #include "content/common/browser_plugin/browser_plugin_constants.h"
 #include "content/common/browser_plugin/browser_plugin_messages.h"
 #include "content/renderer/browser_plugin/browser_plugin.h"
 #include "content/renderer/render_thread_impl.h"
@@ skipping 82 matching lines @@
     it.Advance();
   }
 
   Send(new BrowserPluginHostMsg_PluginAtPositionResponse(
        message.routing_id(), instance_id, request_id, local_position));
 }
 
 void BrowserPluginManagerImpl::OnUnhandledSwap(const IPC::Message& message,
                                                int instance_id,
                                                const gfx::Size& size,
-                                               std::string mailbox_name,
+                                               gpu::Mailbox mailbox_name,
                                                int gpu_route_id,
                                                int gpu_host_id) {
   // After the BrowserPlugin object sends a destroy message to the
   // guest, it goes away and is unable to handle messages that
   // might still be coming from the guest.
   // In this case, we might receive a BuffersSwapped message that
   // we need to ACK.
   // Issue is tracked in crbug.com/170745.
   Send(new BrowserPluginHostMsg_BuffersSwappedACK(
       message.routing_id(),
       instance_id,
       gpu_route_id,
       gpu_host_id,
       mailbox_name,
       0));
 }
 
 }  // namespace content